Optical information recording medium

ABSTRACT

An optical information recording medium provided on a substrate with a recording layer including a dye layer; wherein the dye layer contains a cyanine dye; and the recording layer enables a recording and reproducing to be effected with a laser beam having a wavelength falling within a range of 620 nm to 690 nm; a refractive index &#34;n&#34; of the recording layer being in a range of 1.6 to 4.0 and an extinction coefficient &#34;k&#34; of the a recording layer being in a range of 0.01 to 0.45 when the laser beam having the wavelength is applied thereto; and the recording layer exhibiting a maximum absorption peak wavelength and a second largest absorption peak wavelength falling within a range of 500 nm to 655 nm as measured by means of a visible ultraviolet spectrometer. The dye may be a trimethine-base cyanine dye.

BACKGROUND OF THE INVENTION

This invention relates to an optical information recording medium ofwrite once (through a heat mode) type such as DVD-R, which is capable ofperforming a recording or reproducing data by means of a laser beam of ashorter wavelength.

The CD-R is well known as a means for recording and reproducing datasuch as images of character and graphic or music. The CD-R now availableis formed by making use of a recording material, which is capable ofrecording and reproducing with a laser beam of 770 to 830 nm inwavelength and selected based on its absorbency and optical parameters(in particular, refractive index "n" and extinction coefficient "k").For example, an optical disk comprising a dye layer containingpentamethine-based cyanine dye is employed.

Recently however, DVD-R (a digital video disk or a digital versatiledisk), which is capable of recording and reproducing in high densitywith a red laser beam of 620 to 690 nm in wavelength for instance, whichis shorter than the laser beam employed in the aforementioned CD-R, isnow propagated as new media of the next generation.

Since the wavelength zone for performing the recording and reproducingin the DVD-R differs from that of the CD-R, the criteria for selectingthe recording material to be employed for the CD-R cannot be applied tothe DVD-R, and hence new selection criteria are required to beestablished from a viewpoint peculiar to the DVD-R.

Since the recording and reproducing of data in the CD-R as a write oncetype optical information recording medium are performed by making use ofa semiconductor laser having a wavelength of 770 to 830 nm (λ₁), it isconsidered that a recording layer comprising a dye layer enabling anadditional recording should preferably be formed on a transparentsubstrate in such a manner that the optical parameters in particular,the refractive index "n" and extinction coefficient "k" of the recordinglayer at the aforementioned λ₁ fall in the ranges of: 1.6 <n<4.0 and0.01 <k<0.2 for the purpose of ensuring a suitable reflectance (65% ormore) before recording and a modulated amplitude after recording.Namely, if refractive index; n falls outside the aforementioned rangesin the CD-R, it is impossible to assure a reflectance of 65% or more inthe recording/reproducing wavelength zone thereof. On the other hand, ifextinction coefficient; k falls outside the aforementioned ranges in theDVD-R, it is not only impossible to assure a sufficient reflectance butalso impossible to perform a high quality recording. It is generallyconsidered that, in order to assure the aforementioned preferable rangesof these optical parameters n and k, the maximum absorption wavelengthλ₂ of the recording layer should preferably be confined to the range of600 to 750 nm. However, since the recording and reproducing areperformed at a wavelength of 620 to 690 nm (λ₂) in the DVD-R, i.e. whichis far shorter than 770 nm, the aforementioned ranges of n and k, whichare preferable for CD-R are no more preferable for DVD-R. Therefore, itis impossible for the DVD-R to suitably perform the recording andreproducing by making use of the recording materials which have beenemployed for the CD-R.

BRIEF SUMMARY OF THE INVENTION

Therefore a first object of this invention is to provide an opticalinformation recording medium which is formed of a recording materialwhich makes it possible to suitably select an optical parameters and amaximum absorption wavelength in relative to a laser beam of shorterwavelength for performing the recording and reproducing of the DVD-R.

A second object of this invention is to provide an optical informationrecording medium which makes it possible to select a recording materialexhibiting suitable optical parameters by selecting the chemicalstructure of a dye.

A third object of this invention is to provide an optical informationrecording medium which makes it possible to select a recording materialexhibiting suitable optical parameters by the co-use of a plurality ofdyes.

A fourth object of this invention is to provide an optical informationrecording medium which makes it possible to adjust the recordingsensitivity by suitably selecting or controlling the optical parametersthereof.

A fifth object of this invention is to provide an optical informationrecording medium which makes it possible to adjust the opticalparameters without employing additives, to suppress an accumulation ofheat during recording, and to perform the recording of lower jitter.

The present inventors have made an intensive study to solve theaforementioned problems and performed a simulation on the reflectancewherein the recording layer was assumed as exhibiting a refractive index"n" in the range of 1.6 to 4.0 and an extinction coefficient "k" in therange of 0.01 to 0.45 under a wavelength ranging from 620 nm to 690 nm,thereby to obtain the results as shown in FIGS. 1 and 2 (when thewavelength is 620 nm), and FIGS. 3 and 4 (when the wavelength is 690 nm)(the reflectance was calculated according to a method described in"DYESTUFFS & CHEMICALS", Vol.37, No.7, 1992).

It will be seen from these results that since the reflectance of arecording material for CD-R is required to be 65% or more in view ofrecording, it is impossible to ensure a sufficient reflectance when theextinction coefficient "k" is 0.45. Whereas, in the case of DVD-R, sincethe reflectance of the recording material is required to be more than45%, it is possible to perform a recording even if k=0.45 if the filmthickness of the recording material is less than 110 nm, more preferablyless than 90 nm.

This simulation was performed by making use of a film formed on asubstrate having no groove. Therefore, if an actual optical disk whichis provided with grooves is employed in this simulation, the reflectancemay be lowered more or less. However, even if the interference by thesegrooves is taken into account, the recording material may be suited fora practical use, since there was a sufficient margin in reflectance (areflectance higher than 40%) in the aforementioned simulation.

The present inventors have found that when trimethine cyanine dye isemployed for instance as a material exhibiting these optical parametersconforming to the wavelength of 620 nm to 690 nm, the maximum absorptionwavelength and the second largest absorption wavelength can be confinedto 500 nm to 655 nm.

Namely, according to this invention, there is provided (1) an opticalinformation recording medium provided on a substrate with a recordinglayer including a dye layer; wherein said dye layer contains a cyaninedye; and said recording layer enables a recording and reproducing to beeffected with a laser beam having a wavelength falling within a range of620 nm to 690 nm; a refractive index "n" of said a recording layer beingin a range of 1.6 to 4.0 and an extinction coefficient "k" of said arecording layer being in a range of 0.01 to 0.45 when said laser beamhaving said wavelength is applied thereto; and said a recording layerexhibiting a maximum absorption peak wavelength and a second largestabsorption peak wavelength falling within a range of 500 nm to 655 nm asmeasured by means of a visible ultraviolet spectrometer.

This invention further provides (2) an optical information recordingmedium as set forth in (1), wherein said dye layer contains one or morekinds of trimethine-based cyanine dye.

This invention further provides (3) an optical information recordingmedium as set forth in (2), wherein said trimethine-based cyanine dye isa compound represented by the following general formula [1].

This invention further provides (4) an optical information recordingmedium as set forth in (3), wherein said trimethine-based cyanine dye isan asymmetry trimethine cyanine dye wherein a ring structure "A" differsfrom a ring structure "A'". ##STR1## wherein "A" represents any one ofthe following general formulas [2], [3], [4] and [5]; ##STR2## "A'"represents any one of the following general formulas [6], [7], [8] and[9]; ##STR3##

"A" and "A'" may be the same or different from each other (where D₁ andD₂ may be the same or different from each other and are individuallyhydrogen atom, alkyl, alkoxy, hydroxyl, halogen atoms, carboxyl,alkoxycarboxyl, alkylcarboxyl, alkylhydroxyl, aralkyl, alkenyl,alkylamide, alkylamino, alkylsufonamide, alkylcarbamoyl, alkylsulfamoyl,alkylsulfonyl, phenyl, cyano, ester, nitro, acyl, allyl, aryl, aryloxy,alkylthio, arylthio, phenylazo, pyridinoazo, alkylcarbonylamino,sulfonamide, amino, alkylsulfone, thiocyano, mercapt, chlorosulfone,alkylazomethine, alkylaminosulfone, vinyl or sulfone group; p and qrespectively represents an integer of 1 or more); R and R' may be thesame or different from each other and are individually substituted orunsubstituted alkyl, carboxyl, alkoxycarbonyl, alkoxycarboxyl, alkoxyl,alkylhydroxyl, aralkyl, alkenyl, alkylamide, alkylamino,alkylsufonamide, alkylcarbamoyl, alkylsulfamoyl, hydroxyl, halogenatoms, alkylalkoxyl, alkyl halide, alkylsulfonyl, alkylcarboxyl oralkylsulfonyl which are bonded to a metallic ion or alkyl, phenyl,benzyl or alkylphenyl group; and X⁻ is an anion selected from the groupconsisting of halogen atoms, PF₆ ⁻, SbF₆ ⁻, H₃ PO₄, perchloric acid,hydroborofluoric acid, benzenesulfonic acid, toluenesulfonic acid,alkylsulfonic acid, benzenecarboxylic acid, alkylcarboxylic acid,trifluoromethylcarboxylic acid, periodic acid and SCN⁻.

This invention further provides specific inventions in which theaforementioned invention is further limited.

Specific examples of trimethine-based cyanine dye are those set forth inthe following examples.

In this invention, the recording layer is formed so as to enable arecording and reproducing to be effected with a laser beam having awavelength falling within a range of 620 nm to 690 nm (λ₂). This, inturn, means that the recording layer is made available for use in DVD-R.

The expression of the "recording layer" means in this invention not onlya recording layer comprising a single or plural dye layers enabling pitsto be formed thereon with a laser beam, but also an enhancing layer madeof a resin for instance for adjusting the refractive index or filmthickness of the optical information recording medium with a view toadjust the optical property of the optical information recording medium,and also an intermediate layer to be interposed between a substrate anda dye layer or between a plurality of dye layers.

Furthermore, in this invention, the recording layer is designed suchthat the optical parameters thereof, i.e. a refractive index "n" and anextinction coefficient "k" at the aforementioned λ₂ are confined to theranges of 1.6<n<4.0 and 0.01<k<0.45, and that a maximum absorption peakwavelength and a second largest absorption peak wavelength thereof fallwithin a range of 500 nm to 655 nm as measured by means of a visibleultraviolet spectrometer. It will be clear from the comparison of theselimitations with those of the CD-R that the above limitations on theoptical parameters which correspond to the limitations of opticalparameters in the CD-R where a laser beam having a wavelength of 770 to830 nm (λ₁) is employed differ fundamentally from the limitations ofoptical parameters in the CD-R though they may be partially overlapped.On the other hand, the above limitation on the maximum absorption peakwavelength can be compared with the maximum absorption peak wavelengthof 600 to 750 nm in the CD-R, finding that the range of the maximumabsorption peak wavelength is shifted to a lower wavelength side fromthe range of the maximum absorption peak wavelength in the CD-R.

If the aforementioned optical parameters "n" and "k" fall outside theaforementioned ranges, it becomes impossible to ensure a sufficientreflectance before recording and push-pull before and after recording,so that it would be impossible to assure the tracking during recordingand reproducing, and also to assure the modulated amplitude afterrecording.

It is preferable for the purpose of optimizing the optical properties ofthe recording layer such as the optical parameters and maximumabsorption wavelength to incorporate one or more kinds oftrimethine-based cyanine dye having a different optical parameter into asingle or plural dye layers included in the recording layer. It ispossible with the employment of a dye layer where plural kinds oftrimethine-based cyanine dye are contained to obtain a compositespectrum from the combination of absorption spectra of these differentkinds of dye so as to make this composite spectrum optimal to the laserbeam to be employed for the recording and reproducing in the DVD-R.Namely, it is possible to optimize the optical parameters by mixingplural kinds of dye each differing in optical parameters, thus providinga recording layer comprising an optimized dye layer and hence making itpossible to adjust the recording sensitivity.

This trimethine-based cyanine dye is formed of a molecule whose backbonechain contains three carbon atoms, i.e. which is shorter by two carbonatoms as compared with the pentamethine-based cyanine dye which has beenemployed as a recording material in CD-R. Because of this, it ispossible to confine the maximum absorption wavelength and the secondlargest absorption wavelength to the range of 500 nm to 655 nm, which isshifted to the shorter wavelength side as compared with the range of 600nm to 750 nm in maximum absorption wavelength of the pentamethine-basedcyanine dye. Therefore, it is possible to select a suitable dyeexhibiting the aforementioned preferable ranges of optical parameters"n" and "k" from various kinds of trimethine-based cyanine dye, thusobtaining a recording material which enables the recording andreproducing to be performed with a laser beam of shorter wavelengthwhich is suited for use in the DVD-R.

The aforementioned trimethine-based cyanine dye which is applicable inthis invention can be optionally selected from the compounds repreformudby the aforementioned general formula [1] wherein "A" can be optionallyselected from the general formulas [2], [3], [4] and [5], "A'" can beoptionally selected from the general formulas [6], [7], [8] and [9], and"A" and "A'" can be optionally combined. For example, the compounds ofthe general formulas [2] may be optionally combined with any one of thecompounds of the general formulas [6], [7], [8] and [9]. Likewise, thecompounds of the general formulas [3], [4] and [5] may be optionallycombined with any one of the compounds of the general formulas [6], [7],[8] and [9]. The "p" and "q" in the substituent groups (D₁)_(p) and(D₂)_(q) in "A" and "A'" are individually an integer of 1 or more.Preferable examples of this trimethine-based cyanine dye are asymmetrictrimethine-based cyanine dyes wherein the ring structures disposed onboth sides of the cyanine molecule differ from each other, i.e. it ispreferable to employ an asymmetric trimethine-based cyanine dye wherethe ring structure of "A" disposed on one side of the trimethine chain,which is selected from the general formulas [2], [3], [4] and [5]differs from the ring structure of "A'" disposed on the other side ofthe trimethine chain, which is selected from the general formulas [6],[7], [8] and [9]. The asymmetric compound of this kind advantageous inthat it exhibits an absorption at the aforementioned wavelength λ₂ whichis sharp in absorption wavelength distribution, i.e. short in skirtportion thereof, that it exhibits an improved absorbency per unit filmthickness of the dye layer, that it exhibits an improved recordingefficiency, that it requires no additive for adjusting the opticalparameters, which might be required if the dye layer is constituted byonly symmetrical compounds, that it is capable of obtaining an optimaloptical parameters by itself thereby making it possible to employ only asingle dye component and hence to suppress a heat accumulation and torecord with a much lower jitter, and that it is capable of enhancing therecording sensitivity thereof.

R and R' in the aforementioned general formula [1] should preferably bedifferent from each other so as to make it possible to adjust thesolubility to a solvent of the dye. A and A' in the aforementionedgeneral formula [1] should preferably be provided with the substituentgroups (D₁)_(p) and (D₂)_(q) so as to make it possible to control themoisture resistance and weatherability of the dye. The kind of X⁻ may besuitably changed so as to control the heat decomposability of the dye bya laser beam, thereby making it possible to control the shape of pits atthe occasion of recording.

It is possible by the employment of the above-mentioned trimethine-basedcyanine dye to improve the recording sensitivity of the recording layerto a laser beam having a wavelength ranging from 620 to 690 nm, inparticular from 630 to 655 nm, and to provide a DVD-R which is excellentin terms of jitter, modulated amplitude and asymmetry when reproducing(play-back).

The method for synthesizing these dyes can be performed by the methoddescribed in "The Chemistry of Synthetic Dyes; Vol. 14".

The manufacture of the optical information recording medium according tothis invention can be performed as follows.

First of all, a cyanine dye represented by the aforementioned generalformula [1] is dissolved in a solvent to obtain a dye solution, which isthen coated on a transparent substrate. The solvent to be employed inthe preparation of this dye solution may be selected from chloroform,dichloroethane, a fluorine-based solvent such as fluorinated alcohol,methylethyl ketone, dimethylformamide, methanol, toluene, cyclohexanone,acetylacetone, diacetone alcohol, cellosolves such as methyl cellosolve,and dioxane. The mixing ratio of the cyanine dye in this case shouldpreferably be 1 to 10% by weight.

As for the material for the substrate to be employed in this invention,glass, or plastics such as epoxy resin, methacryl resin, polycarbonateresin, polyester resin, polyvinyl chloride resin and polyolefin resinmay be employed. The substrate may be provided in advance with trackinggrooves or pits, which may be provided with a signal required for anaddress signal.

The coating of the aforementioned cyanine dye on a substrate shouldpreferably be performed by means of a spin-coating method. The filmthickness after being dried of the dye layer may be the same as thatadopted for DVD-R.

The recording layer according to this invention may contain a singletoxygen quencher, a light absorbent, a radical scavenger, etc.

The optical information recording medium according to this invention mayinclude a reflection layer in addition to the recording layer. Thisreflection layer may be provided on its surface with a protective layer.This protective layer may also be deposited on the exposed surface (thesurface from which a laser beam is irradiated) of the substrate.

As for the reflection layer, a film of high reflectivity, such as ametallic film may be employed. This metallic film can be formed by thevapor-deposition or sputtering of a metal such as Au, Al, Ag, Cu, Pt, analloy comprising any of these metals or other kinds of metal, or analloy containing other trace component. The protective layer is formedfor the purpose of protecting or improving the optical informationrecording medium, and can be formed by coating a solution of a radiationcure type resin (such as an ultraviolet cure type resin) on a givensurface by means of spin coating for instance and then curing the coatedlayer.

As a result, an optical disk comprising a substrate provided on itssurface with a recording layer, an reflection layer and any otheroptional layer such as a protective layer can be obtained. The opticaldisk comprising at least a recording layer as an essential layer and anyother optional layer(s) may be superimposed on another optical diskcomprising at least a recording layer as an essential layer and anyother optional layer(s), or one substrate may be laminated on anothersubstrate of an optical information recording medium.

The adhesives and methods for forming this laminated structure may besuitably selected by making use of an ultraviolet-curing resin, acationic-curing resin, a-pressure sensitive adhesive double coated tape,a hot-melt method, a spin-coating method, a dispense method (extrusionmethod), a screen printing method, a roll coating method, etc.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a graph showing changes in reflectance in relative to the filmthickness as the extinction coefficient "k" was varied under a conditionwhere the refractive index "n" was set to n=4.0 at a wavelength of 620nm, which were obtained in a simulation;

FIG. 2 is a graph showing changes in reflectance in relative to the filmthickness as the refractive index "n" was varied under a condition wherethe extinction coefficient "k" was set to k=0.2 at a wavelength of 620nm, which were obtained in a simulation;

FIG. 3 is a graph showing changes in reflectance in relative to the filmthickness as the extinction coefficient "k" was varied under a conditionwhere the refractive index "n" was set to n=4.0 at a wavelength of 690nm, which were obtained in a simulation;

FIG. 4 is a graph showing changes in reflectance in relative to the filmthickness as the refractive index "n" was varied under a condition wherethe extinction coefficient "k" was set to k=0.2 at a wavelength of 690nm, which were obtained in a simulation;

FIG. 5 is a graph showing the absorption spectra of the photosensitivedye films obtained in Examples of this invention and ComparativeExamples; and

FIG. 6 is a plan view for illustrating method of calculating thepush-pull.

DETAILED DESCRIPTION OF THE INVENTION

This invention will be further explained in detail with reference to thefollowing preferred embodiments.

A polycarbonate substrate provided with a track pitch 0.74 μm in length(it may be 0.80 μm) and only wobble signal (pre-pit may also beincluded) was employed. Trimethine-based cyanine dyes for the dye layerof a recording layer were selected as follows. Namely, dyes representedby the aforementioned general formula [1] where (1) "A" is formed of acombination of the general formulas [2] and [3], "A'" is formed of acombination of the general formulas [6] and [7], (2) D₁ and D₂ are bothhydrogen atom, or (3) D₁ is a lower alkyl such as methyl and p is 1 andD₂ is hydrogen atom or a lower alkyl such as methyl and q is 1 (in thiscase, each of "A" and "A'" is preferably benzene ring), (4) R and R' arethe same or different from each other and are individually a lower alkylsuch as ethyl, butyl, amyl, etc., (5) X⁻ is an anion of perchloric acidor of iodine were selected. Then, a solution of dye meeting theaforementioned conditions (1) to (5) was respectively prepared andcoated on the polycarbonate substrate to form a dye layer. Thereafter, areflection layer consisting of Au or Al was deposited on the dye layerby means of sputtering. A protective layer comprising anultraviolet-curing resin was further spin-coated on the reflectionlayer. Then, a pair of the optical disks thus obtained were superimposedvia an adhesive layer comprising an ultraviolet-curing resin which wasspin-coated on the polycarbonate substrate, thereby obtaining alaminated-disk type optical disk.

Each of the dyes employed herein is formed of a molecule whose backbonechain is consisted of trimethine chain having three carbon atoms, towhich functional groups are added, thereby making it possible to confinethe maximum absorption wavelength to a range of 500 to 655 nm, inparticular to a range of 560 to 615 nm, and also to confine the opticalparameters to 1.6<n<4.0 and 0.01<k<0.45, in particular to 2.1<n<2.7 and0.03<k<0.41. Accordingly, it is possible to select only one kind of dyeas a single dye component, and it is also possible to select a pluralityof dyes which are mixed together to obtain an optimal optical parametersfalling within the aforementioned ranges. Especially, it is possible tooptimize the optical parameters in the wavelength range of 620 to 690nm, thus making it possible to provide a DVD-R which enables therecording and reproducing to be performed with a laser beam of 620 to690 nm, in particular 630 to 670 nm in wavelength.

If the optical parameters can be optimized, the adjustment of thesensitivity of the tracking signal represented for example by thepush-pull as well as the adjustment of reflectance would become easy.When a trimethine-based dye which is asymmetric in ring structure isemployed singly for a recording layer, the absorption wavelengthdistribution of the recording layer to a laser beam would become sharp,i.e. the skirt portion of the spectrum becomes short due to itsassociation state, etc. Namely, when the absorption spectrum is sharp asmentioned above, the absorbency per unit film thickness of the dye layerwould be improved, thus enhancing the recording efficiency. It isimpossible, when a trimethine-based dye of symmetric type (i.e.symmetrical in ring structure) is employed, to adjust the opticalparameters unless a plurality of trimethine-based dyes differing in kindfrom each other are employed and mixed together, whereas in the case ofa trimethine-based dye of asymmetric type (i.e. asymmetrical in ringstructure) is employed, the optical parameters thereof can be adjustedby itself so that additional material is no more required for theadjustment of the optical parameters. Therefore, it is possible toemploy only a single dye component, thus improving the recordingefficiency, suppressing a heat accumulation and making it possible torecord a much lower jitter.

This invention will be further explained in detail with reference to thefollowing examples.

EXAMPLE 1

A transparent polycarbonate substrate having a thickness of 0.6 mm, anouter diameter of 120 mm and provided with a spiral groove 0.32 μm inwidth, 100 nm in depth and 0.74 μm in pitch was molded by means of aninjection molding method.

Then, a trimethine-based cyanine dye represented by the followinggeneral formula [10] (NK-4285, n=2.70, k=0.41 in a wavelength of 635 nm;Japanese Research Institute for Photosensitizing Dye Co., Ltd.) and atrimethine-based cyanine dye represented by the following generalformula [11] (NK-4270, n=2.41, k=0.0 in a wavelength of 635 nm; JapaneseResearch Institute for Photosensitizing Dye Co., Ltd.) were mixedtogether at a weight ratio of 25:75 to obtain a mixture. Then, thismixture was dissolved in 2,2,3,3-tetrafluoro-1-propanol (Tokyo KaseiKogyo Co., Ltd.; hereinafter referred to as TFP) to obtain a solutioncontaining 3% by weight of the aforementioned mixture. This solution wasthen coated on the substrate by means of a spin-coating method to obtaina recording layer consisting of a photosensitive dye film having a filmthickness of 110 nm. ##STR4##

The maximum absorption wavelength and optical parameters of thisrecording layer were measured by irradiating a laser beam having awavelength of 635 nm, the results being shown in Table 1. It will beseen from the results that the optical parameters "n" and "k" meet theconditions of 1.6<n <4.0 and 0.01<k <0.45.

When the absorption spectrum of the recording layer (the wavelengthdependency of the absorbency (Abs) under a laser beam wavelength rangingfrom 400 to 800 nm) was measured by making use of a visible ultravioletspectrometer (U-4000; Hitachi, Ltd.) to obtain the results as shown in abroken line in FIG. 5. As seen from FIG. 5, the maximum absorption peakwavelength and the second largest absorption peak wavelength of thisrecording layer fall within the range of 500 to 655 nm.

Next, a reflection layer consisting of an Au film having a filmthickness of 80 nm was formed, by means of sputtering method, on thesurface of a portion (a region 44 mm to 117 mm in diameter) of therecording layer deposited on the substrate.

Furthermore, an ultraviolet-curing resin (SD-211; Dainippon Ink &Chemicals Inc.) was spin-coated on the surface of the reflection layer,and then allowed to cure by irradiating ultraviolet rays to the coatedlayer to obtain a protective film having a film thickness of 5 μm.

Then, an ultraviolet-curing resin (SD-318; Dainippon Ink & ChemicalsInc.) was dripped on the protective film on the portion of the recordinglayer. Thereafter, another substrate which was molded in the same manneras mentioned above was placed on the surface of the substrate carryingthereon the aforementioned ultraviolet-curing resin. After the resininterposed between these substrates was allowed to disperse by means ofa spin-coating method, ultraviolet rays was irradiated, via thesubstrate which was molded in the same manner, to the ultraviolet-curingresin to cure it, thereby forming an adhesive region 25 μm in thicknessand 32 mm to 120 mm in diameter and obtaining a laminated-disk typeoptical disk.

Then, a recording was performed on this optical disk by making use of arecording machine (DDU-1000; numerical aperture=0.6, and laserwavelength=635 nm; Pulsetec Industria Co., Ltd.) under a linear velocityof 3.5 m/sec., and the jitter was measured by making use of a timeinterval analyzer (TA-320; Yokogawa Electric Co., Ltd.). According tothe specification of disc, the Data to Clock Jitter (jitter) is a datawhich can be obtained by normalizing the deviation value σ of thebinarize.data.edge signal by taking the channel bit length=38.23 nsec.as 100%. The evaluation of jitter is determined based on g-16 signalmodulation where the minimum pit length is set to 0.4 μm and the linearvelocity is set to 3.5/sec. The value of jitter should be at most 8% orpreferably 8% or less in view of preventing an accidental demodulation(decord) of the signal.

The push-pull (to be referred to as PP hereinafter) which indicates thetracking sensitivity was measured and evaluated by making use of a laserbeam 650 nm in wavelength. In this measurement, a laser beam (circular)was irradiated onto the groove and the reflected light from a detectorwhich was partitioned into four sections (a four-partitionedphotodetector) was converted into an electric voltage, the resultantvalue being represented by (I₁ +I₃)-(I₂ +I₄)/(I₁ +I₂ +I₃ +I₄). The arrowof Y-axis denotes a tangential direction. If this PP is too low, it isimpossible to perform the tracking. Therefore, the value of PP shouldpreferably be 0.13 or more. Furthermore, the reflectance and themodulated amplitude after recording (I₃ /I_(top), I₁₄ /I_(top)) werealso measured by making use of a laser beam 650 nm in wavelength.

In this case, the value of I_(top) is a maximum reflection lightquantity under HF (EFM) signal and almost identical with the value of amaximum reflection light quantity of I₁₄. I₃ is a signal of opticalmodulation component which can be derived from a difference in lightquantity between the light quantity that is diffracted at the shortestpit to be recorded in the groove to be recorded and then returned to theobjective lens and the light quantity that is reflected at the non-pitportion and then returned to the objective lens. I₁₄ is a signal ofoptical modulation component which can be derived from a difference inlight quantity between the light quantity that is diffracted at thelongest pit to be recorded in the groove to be recorded and thenreturned to the objective lens and the light quantity that is reflectedat the non-pit portion and then returned to the objective lens.

If the reflectance is too low, the focus would become unstable.Therefore, the reflectance should preferably be 45% or more. The resultsof the measurements as illustrated above are shown in Table 1.

In this Example, a mixture consisting of two kinds of dyes each beingsymmetrical in ring structures which are disposed on both sides of thetrimethine chain was employed. However, it was possible to perform therecording with a laser beam of 635 nm in wavelength and to perform thereproducing with a laser beam of 650 nm in wavelength. It will be seenthat the reflectance, push-pull and modulated amplitude were all high,but the jitter was not so high. The fact that the jitter was not so highmeans that the accumulation of heat was also not so high. Excellency inmodulated amplitude and in jitter means that the play-back(reproduction) sensitivity is good.

EXAMPLE 2

An optical disk was manufactured in the same manner as illustrated inExample 1 except that the sputtering was performed by substituting Alfor Au and a reflection layer consisting of an Al film having athickness of 80 nm was formed. The recording was also performed in thesame manner as illustrated in Example 1. The results of measurementsobtained are shown in Table 1.

Although the material for the reflection layer was altered from thatemployed in Example 1, it was possible to perform the recording with alaser beam of 635 nm in wavelength and to perform the reproducing with alaser beam of 650 nm in wavelength. Jitter was not so high, and thepush-pull, modulated amplitude and reflectance were found to be inferiormore or less as compared with those of Example 1, but they were not sobad.

EXAMPLE 3

A trimethine-based cyanine dye represented by the following generalformula [12] (NK-4321; Japanese Research Institute for PhotosensitizingDye Co., Ltd.) was dissolved in TFP to obtain a solution containing 3%by weight of the aforementioned dye. This solution was then coated onthe same kind of substrate as employed in Example 1 by means of aspin-coating method to obtain a recording layer consisting of aphotosensitive dye film having a film thickness of 90 nm. ##STR5##

The maximum absorption wavelength (the maximum absorption peakwavelength) and optical parameters of this recording layer were measuredin the same manner as illustrated in Example 1 by irradiating a laserbeam having a wavelength of 635 nm, the results being shown in Table 1.Further, the absorption spectrum of the recording layer was measured inthe same manner as illustrated in Example 1 to obtain the results asshown in a solid line in FIG. 5. As seen from FIG. 5, the maximumabsorption peak wavelength and the second largest absorption peakwavelength of this recording layer fall within the range of 500 to 655nm.

Next, a reflection layer consisting of an Au film having a filmthickness of 80 nm was formed, by means of sputtering method, on thesurface of a portion (a region 44 mm to 117 mm in diameter) of therecording layer deposited on the substrate.

Furthermore, an ultraviolet-curing resin (SD-211; Dainippon Ink &Chemicals Inc.) was spin-coated on the surface of the reflection layerin the same manner as illustrated in Example 1.

Then, a laminated-disk type optical disk was manufactured in the samemanner as illustrated in Example 1 by superimposing a pair of thesubstrates with an ultraviolet-curing resin being interposedtherebetween.

Then, a recording was performed on this optical disk in the same manneras illustrated in Example 1. The results of the measurements are shownin Table 1.

In this Example, a dye which is asymmetrical in ring structures disposedon both sides of the trimethine chain was employed. However, it waspossible to perform the recording with a laser beam of 635 nm inwavelength and to perform the reproducing with a laser beam of 650 nm inwavelength. It will be seen that the push-pull was high, but the jitterwas low, and that the modulated amplitude was large and the reflectancewas not so small. The fact that the jitter was low means that theaccumulation of heat was also low. Excellency in modulated amplitude andin jitter means that the play-back (reproduction) sensitivity is good.

EXAMPLE 4

An optical disk was manufactured in the same manner as illustrated inExample 3 except that the sputtering was performed by substituting Alfor Au and a reflection layer consisting of an Al film having athickness of 80 nm was formed. The measurements were performed also inthe same manner as illustrated in Example 1. The results of measurementsobtained are shown in Table 1.

Although the material for the reflection layer was altered from thatemployed in Example 3, it was possible to perform the recording with alaser beam of 635 nm in wavelength and to perform the reproducing with alaser beam of 650 nm in wavelength. Jitter was very small, and thepush-pull, modulated amplitude and reflectance were found to be inferiormore or less as compared with those of Example 3, but they were not sobad.

EXAMPLE 5

A trimethine-based cyanine dye represented by the aforementioned generalformula [12] (NK-4321) and a trimethine-based cyanine dye represented bythe aforementioned general formula [10] (NK-4285) were mixed together ata weight ratio of 75:25 to obtain a mixture. This mixture was thendissolved in TFP to obtain a solution containing 3% by weight of theaforementioned mixture of dyes. This solution was then coated on asubstrate by means of a spin-coating method to obtain a recording layerconsisting of a photosensitive dye film having a film thickness of 100nm.

The maximum absorption wavelength and optical parameters of thisrecording layer were measured in the same manner as illustrated inExample 1 by irradiating a laser beam having a wavelength of 635 nm, theresults being shown in Table 1.

Next, a reflection layer consisting of an Au film having a filmthickness of 90 nm was formed, by means of sputtering method, on thesurface of a portion (a region 44 mm to 117 mm in diameter) of therecording layer deposited on the substrate.

Furthermore, an ultraviolet-curing resin was spin-coated on the surfaceof the reflection layer in the same manner as illustrated in Example 1.Then, a laminated-disk type optical disk was manufactured in the samemanner as illustrated in Example 1 by superimposing a pair of thesubstrates with an ultraviolet-curing resin being interposedtherebetween.

Then, a recording was performed on this optical disk in the same manneras illustrated in Example 1. The results of the measurements are shownin Table 1.

In this Example, a mixture of two kinds of dye was employed, wherein oneof the dyes was asymmetrical in ring structures disposed on both sidesof the trimethine chain was employed (the same as employed in Example3), whereas the other one of the dyes was symmetrical in ring structuresdisposed on both sides of the trimethine chain was employed (the oneemployed in Example 1). Furthermore, with a view to slightly adjust theoptical parameters, a little amount of the latter dye was added to theformer dye. It was also possible to perform the recording with a laserbeam of 635 nm in wavelength and to perform the reproducing with a laserbeam of 650 nm in wavelength. It will be seen that the jitter was low,the reflectance, push-pull and modulated amplitude were not so bad.

EXAMPLE 6

An optical disk was manufactured in the same manner as illustrated inExample 5 except that the sputtering was performed by substituting Alfor Au and a reflection layer consisting of an Al film having athickness of 80 nm was formed. The recording was performed and thenmeasurements was performed in the same manner as illustrated inExample 1. The results of measurements obtained are shown in Table 1.

Although the material for the reflection layer was altered from thatemployed in Example 5, it was possible to perform the recording with alaser beam of 635 nm in wavelength and to perform the reproducing with alaser beam of 650 nm in wavelength. Jitter was very small, and thepush-pull, modulated amplitude and reflectance were found to be inferiormore or less as compared with those of Example 5, but they were not sobad.

EXAMPLE 7

A trimethine-based cyanine dye represented by the aforementioned generalformula [10] (NK-4285) was dissolved in a Cellosolve-based solvent toobtain a solution containing 3% by weight of the aforementioned dye.This solution was then coated on the surface of a substrate by means ofa spin-coating method to obtain a recording layer consisting of aphotosensitive dye film having a film thickness of 40 nm.

The maximum absorption wavelength and optical parameters of thisrecording layer were measured in the same manner as illustrated inExample 1 by irradiating a laser beam having a wavelength of 635 nm, theresults being shown in Table 1.

Next, a reflection layer consisting of an Au film having a filmthickness of 80 nm was formed, by means of sputtering method, on thesurface of a portion (a region 44 mm to 117 mm in diameter) of therecording layer deposited on the substrate.

Furthermore, an ultraviolet-curing resin was spin-coated on the surfaceof the reflection layer in the same manner as illustrated in Example 1.Then, a laminated-disk type optical disk was manufactured in the samemanner as illustrated in Example 1 by superimposing a pair of thesubstrates with an ultraviolet-curing resin being interposedtherebetween.

Then, a recording was performed on this optical disk in the same manneras illustrated in Example 1. The results of the measurements are shownin Table 1.

In this Example, a dye which is symmetrical in ring structures disposedon both sides of the trimethine chain was employed. However, it waspossible to perform the recording with a laser beam of 635 nm inwavelength and to perform the reproducing with a laser beam of 650 nm inwavelength. It will be seen that the push-pull, reflectance, themodulated amplitude at the occasion of reproduction and jitter cannot besaid as being better than those of the aforementioned Examples. However,the reflectance was not so bad and the modulated amplitude as well asthe jitter were not unmeasurable as that of Comparative Example to bediscussed later.

EXAMPLE 8

An optical disk was manufactured in the same manner as illustrated inExample 7 except that the sputtering was performed by substituting Alfor Au and a reflection layer consisting of an Al film having athickness of 80 nm was formed. The recording was performed and thenmeasurements was performed in the same manner as illustrated inExample 1. The results of measurements obtained are shown in Table 1.

Although the material for the reflection layer was altered from thatemployed in Example 7, it was possible to perform the recording with alaser beam of 635 nm in wavelength and to perform the reproducing with alaser beam of 650 nm in wavelength. The push-pull and modulatedamplitude were found to be inferior more or less as compared with thoseof Example 7, but they were not so bad. With regard to the reflectanceand jitter, they are almost the same as those of Example 7.

EXAMPLE 9

An optical disk was manufactured in the same manner as illustrated inExample 7 except that a trimethine-based cyanine dye represented by thefollowing general formula [13] was substituted for the dye representedby the aforementioned general formula [10]. The recording was performedand then measurements was performed in the same manner as illustrated inExample 1. The results of measurements obtained are shown in Table 1.The maximum absorption wavelength and optical parameters of thisrecording layer were measured in the same manner as illustrated inExample 1 by irradiating a laser beam having a wavelength of 635 nm, theresults being shown in Table 1.

In this Example, a dye employed herein is symmetrical in ring structuresdisposed on both sides of the trimethine chain and differs from thecompound represented by the general formula [10] in the respect thatmethyl group is attached or not attached to the benzene ring in A' ofthe general formula [1]. However, it was possible to perform therecording with a laser beam of 635 nm in wavelength and to perform thereproducing with a laser beam of 650 nm in wavelength. It will be seenthat the push-pull and reflectance were almost the same as those ofExample 7, the modulated amplitude at the occasion of reproduction wasmore excellent as compared with that of Example 7, the jitter cannot besaid as being better than that of the aforementioned Examples. However,the jitter was not unmeasurable as that of Comparative Example to bediscussed later. ##STR6##

It was also confirmed that even if a dye represented by the followinggeneral formula [14] was substituted for the aforementioned dyerepresented by the general formula [13], almost the same results wereobtained. ##STR7##

EXAMPLE 10

An optical disk was manufactured in the same manner as illustrated inExample 9 except that the sputtering was performed by substituting Alfor Au and a reflection layer consisting of an Al film having athickness of 80 nm was formed. The recording was performed and thenmeasurements was performed in the same manner as illustrated inExample 1. The results of measurements obtained are shown in Table 1.

Although the material for the reflection layer was altered from thatemployed in Example 9, it was possible to perform the recording andreproducing with a laser beam of 650 nm in wavelength. The push-pull andmodulated amplitude were found to be inferior more or less as comparedwith those of Example 9, but they were not so bad. With regard to thereflectance and jitter, they are almost the same as those of Example 9.

EXAMPLE 11

An optical disk was manufactured in the same manner as illustrated inExample 3 except that a trimethine-based cyanine dye represented by thefollowing general formula [15] (NK-4370; Japanese Research Institute forPhotosensitizing Dye Co., Ltd.) was substituted for the dye representedby the aforementioned general formula [12]. The recording was performedand then measurements was performed in the same manner as illustrated inExample 1. The results of measurements obtained are shown in Table 1.The maximum absorption wavelength and optical parameters of thisrecording layer were measured in the same manner as illustrated inExample 1 by irradiating a laser beam having a wavelength of 635 nm, theresults being shown in Table 1.

In this Example, a dye employed herein is asymmetrical in ringstructures disposed on both sides of the trimethine chain and differsfrom the compound represented by the general formula [12] in the kind ofX⁻ in the general formula [1], i.e. the anion is formed of perchloricacid or iodine. However, it was possible to perform the recording with alaser beam of 635 nm in wavelength and to perform the reproducing with alaser beam of 650 nm in wavelength. It will be seen that thereflectance, push-pull, the modulated amplitude and jitter were almostthe same as those of Example 3. ##STR8##

EXAMPLE 12

An optical disk was manufactured in the same manner as illustrated inExample 11 except that the sputtering was performed by substituting Alfor Au and a reflection layer consisting of an Al film having athickness of 80 nm was formed. The recording was performed and thenmeasurements was performed in the same manner as illustrated inExample 1. The results of measurements obtained are shown in Table 1.

Although the material for the reflection layer was altered from thatemployed in Example 13, it was possible to perform the recording with alaser beam of 635 nm in wavelength and to perform the reproducing with alaser beam of 650 nm in wavelength. Jitter was very small, and thepush-pull, modulated amplitude and reflectance were found to be inferiormore or less as compared with those of Example 13, but they were not sobad.

Comparative Example 1

A pentamethine-based cyanine dye represented by the following generalformula [16] (NK-3219; Japanese Research Institute for PhotosensitizingDye Co., Ltd.) was dissolved in a Cellosolve-based solvent to obtain asolution containing 3% by weight of the aforementioned dye. Thissolution was then coated on the same kind of substrate as employed inExample 1 by means of a spin-coating method to obtain a recording layerconsisting of a photosensitive dye film having a film thickness of 110nm.

The maximum absorption wavelength and optical parameters of thisrecording layer were measured in the same manner as illustrated inExample 1 by irradiating a laser beam having a wavelength of 635 nm, theresults being shown in Table 1. Further, the absorption spectrum of therecording layer was measured in the same manner as illustrated inExample 1 to obtain the results as shown in a broken line in FIG. 5. Asseen from FIG. 5, the maximum absorption peak wavelength and the secondlargest absorption peak wavelength of this recording layer fall withinthe range of 600 to 750 nm.

Next, a reflection layer consisting of an Au film having a filmthickness of 90 nm was formed, by means of sputtering method, on thesurface of a portion (a region 44 mm to 117 mm in diameter) of therecording layer deposited on the substrate.

Furthermore, an ultraviolet-curing resin was spin-coated on the surfaceof the reflection layer in the same manner as illustrated in Example 1.Then, a laminated-disk type optical disk was manufactured in the samemanner as illustrated in Example 1 by superimposing a pair of thesubstrates with an ultraviolet-curing resin being interposedtherebetween.

Then, a recording was performed on this optical disk in the same manneras illustrated in Example 1. The results of the measurements are shownin Table 1.

In this Comparative Example, a dye employed was a pentamethine-basedcyanine dye, and the maximum absorption wavelength was existed on alonger wavelength side. Additionally, the optical parameter "k" did notmeet the condition of 0.01<k <0.45. As a result, the reflectance was toolow to obtain a data at the occasion of play-back and hence it wasimpossible to perform the play-back with a laser beam having awavelength of 650 nm. ##STR9##

Comparative Example 2

A phthalocyanine dye represented by the following general formula [17]was dissolved in a Cellosolve-based solvent to obtain a solutioncontaining 3% by weight of the aforementioned dye. This solution wasthen coated on the same kind of substrate as employed in Example 1 bymeans of a spin-coating method to obtain a recording layer consisting ofa photosensitive dye film having a film thickness of 90 nm.

The maximum absorption wavelength and optical parameters of thisrecording layer were measured in the same manner as illustrated inExample 1 by irradiating a laser beam having a wavelength of 635 nm, theresults being shown in Table 1.

Next, a reflection layer consisting of an Au film having a filmthickness of 100 nm was formed, by means of sputtering method, on thesurface of a portion (a region 44 mm to 117 mm in diameter) of therecording layer deposited on the substrate.

Furthermore, an ultraviolet-curing resin was spin-coated on the surfaceof the reflection layer in the same manner as illustrated in Example 1.Then, a laminated-disk type optical disk was manufactured in the samemanner as illustrated in Example 1 by superimposing a pair of thesubstrates with an ultraviolet-curing resin being interposedtherebetween.

Then, a recording was performed on this optical disk in the same manneras illustrated in Example 1. The results of the measurements are shownin Table 1. Since the reflectance and push-pull were too poor in thisComparative Example to perform the recording.

In this Comparative Example, a dye employed was a phthalocyanine dyeinstead of a cyanine dye having a methine chain. Additionally, theoptical parameter "k" did not meet the condition of 0.01<k<0.45. As aresult, the reflectance was too low to obtain a data at the occasion ofplay-back and hence it was impossible to perform the play-back with alaser beam having a wavelength of 650 nm.

As explained above, it is more preferable in this invention that thereflectance should be not less than 45%, the push-pull should be notless than 0.13% (not less than 0.40 when both ring structures areasymmetrical or when compounds whose both ring structures aresymmetrical are mixed together), the jitter is not more than 8% (notmore than 7% when both ring structures are asymmetrical) and I₁₄/I_(top) is not less than 60% or more preferably not less than 70%.

As explained above, according to this invention, a recording materialexhibiting suitable optical parameters and a maximum absorptionwavelength in relative to a laser beam of short wavelength forperforming the recording and reproducing of high density is employed.Further, the selection of a recording material exhibiting suitableoptical parameters is realized by suitably selecting the structure of adye. Namely, a trimethine-based cyanine dye where the rings on bothsides of trimethine chain exhibit asymmetrical structure is selected inthis invention. As a result, it is no more required to another kind ofmaterial for controlling the optical parameters of the dye therebymaking it possible to suppress the accumulation of heat at the occasionof recording and to record a low jitter, thus improving the recordingsensitivity. It is also possible to obtain a suitable optical parametersand to adjust the recording sensitivity by suitably selecting acombination of the dye. ##STR10##

                                      TABLE 1                                     __________________________________________________________________________            Max                    Modulated                                              absorption                                                                          Optical          amplitude                                              wavelength                                                                          parameters*                                                                         Reflectance                                                                         Push-pull                                                                          I.sub.3                                                                         I.sub.14                                                                         Jitter                                                                           Record-                                        0 (nm)                                                                              n  k  (%)   (%)  I.sub.top                                                                       I.sub.top                                                                        (%)                                                                              ability                                __________________________________________________________________________    Example                                                                            1  575   2.50                                                                             0.10                                                                             80    0.50 24                                                                              85 8  Yes                                         2  575   2.50                                                                             0.10                                                                             70    0.45 23                                                                              70 8  Yes                                         3  585   2.42                                                                             0.05                                                                             65    0.50 25                                                                              84 6  Yes                                         4  585   2.42                                                                             0.05                                                                             60    0.40 23                                                                              70 7  Yes                                         5  585   2.43                                                                             0.07                                                                             60    0.45 27                                                                              84 7  Yes                                         6  585   2.43                                                                             0.07                                                                             55    0.40 26                                                                              70 7  Yes                                         7  615   2.70                                                                             0.41                                                                             50    0.25 15                                                                              70 8  Yes                                         8  615   2.70                                                                             0.41                                                                             50    0.20 12                                                                              60 8  Yes                                         9  562   2.12                                                                             0.03                                                                             50    0.30 25                                                                              82 8  Yes                                         10 562   2.12                                                                             0.03                                                                             50    0.25 22                                                                              72 8  Yes                                         11 585   2.68                                                                             0.10                                                                             65    0.50 25                                                                              83 7  Yes                                         12 585   2.68                                                                             0.10                                                                             60    0.40 24                                                                              70 7  Yes                                    Comp. Ex.                                                                          1  710   2.01                                                                             1.08                                                                              8    0.30 --                                                                              -- -- Yes                                                                   (Un-                                                                          measur-                                                                       able)                                               2  673   1.58                                                                             0.53                                                                             10    0.30 --                                                                              -- -- Yes                                                                   (Un-                                                                          measur-                                                                       able)                                          __________________________________________________________________________     *Value obtained by laser beam of 635 nm wavelength                       

We claim:
 1. An optical information recording medium provided on asubstrate with a recording layer including a dye layer; wherein said dyelayer contains a cyanine dye; and said recording layer enables arecording and reproducing to be effected with a laser beam having awavelength falling within a range of 620 nm to 690 nm; a refractiveindex "n" of said recording layer being in a range of 1.6 to 4.0 and anextinction coefficient "k" of said recording layer being in a range of0.01 to 0.45 when said laser beam having said wavelength is appliedthereto; and said recording layer exhibiting a maximum absorption peakwavelength and a second largest absorption peak wavelength fallingwithin a range of 500 nm to 655 nm as measured by means of a visibleultraviolet spectrometer.
 2. The optical information recording mediumaccording to claim 1, wherein said dye layer contains one or more kindsof trimethine-based cyanine dye.
 3. The optical information recordingmedium according to claim 2, wherein said trimethine-based cyanine dyeis a compound represented by the following general formula [1];##STR11## wherein "A" represents any one of the following generalformulas [2], [3], [4] and [5]; ##STR12## "A'" represents any one of thefollowing general formulas [6], [7], [8] and [9]; ##STR13## "A" and "A'"may be the same or different from each other (where D₁ and D₂ may be thesame or different from each other and are individually hydrogen atom,alkyl, alkoxy, hydroxyl, halogen atoms, carboxyl, alkoxycarboxyl,alkylcarboxyl, alkylhydroxyl, aralkyl, alkenyl, alkylamide, alkylamino,alkylsufonamide, alkylcarbamoyl, alkylsulfamoyl, alkylsulfonyl, phenyl,cyano, ester, nitro, acyl, allyl, aryl, aryloxy, alkylthio, arylthio,phenylazo, pyridinoazo, alkylcarbonylamino, sulfonamide, amino,alkylsulfone, thiocyano, mercapt, chlorosulfone, alkylazomethine,alkylaminosulfone, vinyl or sulfone group; p and q respectivelyrepresents an integer of 1 or more); R and R' may be the same ordifferent from each other and are individually substituted orunsubstituted alkyl, carboxyl, alkoxycarbonyl, alkoxycarboxyl, alkoxyl,alkylhydroxyl, aralkyl, alkenyl, alkylamide, alkylamino,alkylsufonamide, alkylcarbamoyl, alkylsulfamoyl, hydroxyl, halogenatoms, alkylalkoxyl, alkyl halide, alkylsulfonyl, alkylcarboxyl oralkylsulfonyl which are bonded to a metallic ion or alkyl, phenyl,benzyl or alkylphenyl group; and X⁻ is an anion selected from the groupconsisting of halogen atoms, PF₆ ⁻, SbF₆ ⁻, H₃ PO₄, perchloric acid,hydroborofluoric acid, benzenesulfonic acid, toluenesulfonic acid,alkylsulfonic acid, benzenecarboxylic acid, alkylcarboxylic acid,trifluoromethylcarboxylic acid, periodic acid and SCN⁻.
 4. The opticalinformation recording medium according to claim 3, wherein saidtrimethine-based cyanine dye is an asymmetry trimethine cyanine dyewherein a ring structure "A" differs from a ring structure "A'".
 5. Theoptical information recording medium according to claim 3, wherein saiddye layer contains a trimethine-based cyanine dye comprising acombination of said general formulas [2] or [3] and said generalformulas [6] or [7].
 6. The optical information recording mediumaccording to claim 5, wherein D₁ in said general formulas [2] or [3] andD₂ in said general formulas [6] or [7] are both hydrogen atom.
 7. Theoptical information recording medium according to claim 5, wherein D₁ insaid general formulas [2] or [3] is a lower alkyl group and p is 1, andD₂ in said general formulas [6] or [7] is hydrogen atom or a lower alkylgroup and q is
 1. 8. The optical information recording medium accordingto claim 5, 6 or 7 wherein said trimethine-based cyanine dye is formedof a combination of said general formulas [2] or [6].
 9. The opticalinformation recording medium according to claim 6 or 7 wherein said Rand R' is the same or different from each other and are individually alower alkyl group.
 10. The optical information recording mediumaccording to claim 8 wherein said R and R' is the same or different fromeach other and are individually a lower alkyl group.
 11. The opticalinformation recording medium according to claim 9 wherein said X⁻ is ananion of perchloric acid or an anion of iodine.
 12. The opticalinformation recording medium according to claim 10 wherein said X⁻ is ananion of perchloric acid or an anion of iodine.
 13. The opticalinformation recording medium according to claim 1, wherein said dyelayer contains a trimethine-based cyanine dye comprising a combinationcompounds represented by the following general formulas [10] and [11],which are mixed at a weight ratio of 25:75. ##STR14##
 14. The opticalinformation recording medium according to claim 1, wherein said dyelayer contains a trimethine-based cyanine dye comprising a compoundrepresented by the following general formula [12].
 15. The opticalinformation recording medium according to claim 1, wherein said dyelayer contains a trimethine-based cyanine dye comprising a combinationcompounds represented by the following general formulas [12] and [10],which are mixed at a weight ratio of 75:25.
 16. The optical informationrecording medium according to claim 1, wherein said dye layer contains atrimethine-based cyanine dye comprising a compound represented by thefollowing general formula [10].
 17. The optical information recordingmedium according to claim 1, wherein said dye layer contains atrimethine-based cyanine dye comprising a compound represented by thefollowing general formula [13] or [14].
 18. The optical informationrecording medium according to claim 1, wherein said dye layer contains atrimethine-based cyanine dye comprising a compound represented by thefollowing general formula [15].
 19. The optical information recordingmedium according to claim 1, 2, 3, 4, 5, 6, 7, 13, 14, 15, 16 or 17which further comprises an reflection layer made of gold or aluminum.20. The optical information recording medium according to claim 8 whichfurther comprises an reflection layer made of gold or aluminum.
 21. Theoptical information recording medium according to claim 9 which furthercomprises an reflection layer made of gold or aluminum.
 22. The opticalinformation recording medium according to claim 10 which furthercomprises an reflection layer made of gold or aluminum.
 23. The opticalinformation recording medium according to claim 11 which furthercomprises an reflection layer made of gold or aluminum.
 24. The opticalinformation recording medium according to claim 12 which furthercomprises an reflection layer made of gold or aluminum.